Some Android devices don't route "255.255.255.255" to tethered (through WiFi, Bluetooth, or USB) devices. Subnet-specific broadcast packets (e.g. "192.168.1.255") work better on some of these devices.
The user can work around this by adding their device IP or subnet broadcast address as a device IP, but it would be more convenient if this happens automatically. Broadcast packets to "255.255.255.255" are also more likely to be leaked to the mobile data connection.
In an Android shell, some neighbour IPs can be detected through "cat /proc/net/arp", and "ip n", and the broadcast IPs can be calculated with output from "ip a".